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CBSE Questions for Class 12 Medical Biology Microbes In Human Welfare Quiz 1 - MCQExams.com
CBSE
Class 12 Medical Biology
Microbes In Human Welfare
Quiz 1
During sewage treatment, gases produced include
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Methane, hydrogen sulphide, carbon dioxide and hydrogen.
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Methane, oxygene and hydrogensulphide.
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Hydrogensulphide, methane and sulphur dioxide.
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Hydrogen sulphide, nitrogen and methane.
Explanation
Biogas contains a mixture of different gases which are produced by the breakdown of organic matter in the absence of oxygen. Biogas is composed of methane (CH$$_4$$) and carbon dioxide (CO$$_{2}$$) and may have small amounts of hydrogen sulphide (H$$_{2}$$S), hydrogen (H$$_2$$), moisture and siloxanes.
Thus, the correct answer is option A.
Match the following columns and select the correct option.
Column-I
Column-II
(a)
Clostridium butylicum
(i)
Cyclosporin-A
(b)
Trichoderma polysporum
(ii)
Butyric Acid
(c)
Monascus purpureus
(iii)
Citric Acid
(d)
Aspergillus niger
(iv)
Blood cholesterol-lowering agent
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(a) - (ii), (b) - (i), (c) - (iv), (d) - (iii)
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(a) - (i), (b) - (ii), (c) - (iv), (d) - (iii)
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(a) - (iv), (b) - (iii), (c) - (ii), (d) - (i)
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(a) - (iii), (b) - (iv), (c) - (ii), (d) - (i)
Explanation
a)
Clostridium butylicum
- ii) Butyric acid
b)
Trichoderma polysporum
- i) Cyclosporin -A
C)
Monascus purpureus
- iv) blood cholesterol lowering agent
d)
Aspergillus niger
- iii) Citric acid
So, the correct answer is '
(a) - (ii), (b) - (i), (c) - (iv), (d) - (iii)'
Which of the following can be used as a biocontrol agent in the treatment of plant disease?
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Trichoderma
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Chlorella
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Anabaena
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Lactobacillus
Explanation
Trichoderma sps
are fungi belonging to class Ascomycetes. These fungi are regular components of the soil. They prevent/protect the roots of the plant from pathogenic infection
So, the correct answer is '
Trichoderma
'
Which of the following in sewage treatment removes suspended solids?
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Primary treatment
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Tertiary treatment
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Secondary treatment
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Sludge treatment
Explanation
Sludge is the semisolid material present in contaminated water. It is separated and is decomposed into simpler organic material which can be used to produce compost and help to increase the fertility of the soil.
It is removed in the primary or physical treatment through filtration and sedimentation process.
So, the correct answer is option A.
Which of the following is put into Anaerobic sludge digester for further sewage treatment?
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Floating debris
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Effluents of primary treatment
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Activated sludge
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Primary sludge
Explanation
Activated sludge is put into anaerobic digester for further sewage treatment. It contains biological flocs that contain bacteria and protozoa for further digestion of organic wastes under aerobic conditions.
So, the correct answer is '
Activated sludge'
Select the correct group of biocontrol agents.
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Bacillus thuringiensis
, Tobacco mosaic virus, Aphids
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Trichoderma, Baculovirus, Bacillus thuringiensis
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Oscillatoria, Rhizobium, Trichoderma
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Nostoc, Azospirillium
, Nucleopolyhedrovirus
Explanation
Fungus
Trichoderma
, Baculoviruses(NPV) and
Bacillus thuringiensis
are used as biocontrol agents.
Rhizobium, Nostoc, Azospirillum
and
Oscillatoria
are used as biofertilizers, whereas TMV is a pathogen and aphids are pests that harm crop plants.
So, the correct answer is '
Trichoderma, Baculovirus, Bacillus thuringiensis'
The primitive prokaryotes responsible for the production of biogas from the dung of ruminant animals, include the
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Halophiles
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Thermoacidophiles
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Methanogens
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Eubacteria
Explanation
Methanogens are present in the gut of several ruminant animals such as cows and buffaloes and they are responsible for the production of methane (biogas) from the dung of these animals.
Which one of the following is a wrong matching of a microbe and its industrial product, while the remaining three are correct?
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Monascus purpureus
- Statins
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Acetobacter aceti
- Acetic acid
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Clostridium butylicum
- Lactic acid
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Aspergillus niger
- Citric acid
Explanation
Correct Option: C
Explanation:
Lactic acid is an organic compound produced via fermentation by different microorganisms that are able to use different carbohydrate sources.
Lactic acid bacteria are the main bacteria used to produce lactic acid.
Whereas
Clostridium butyricum
produces butyric acid.
By all of the following ways, bacteria can become resistant to the antibiotic, except -
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Making enzymes that inactivate the drug.
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Becoming impermeable to the drug.
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Modifying the target of the drug.
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Moving away from the drug.
Explanation
Antibiotic resistance occurs when bacteria evolve mechanisms that protect them from the effects of antibiotics.
Bacteria can become resistant to the antibiotic by either producing enzymes or forming an impermeable capsule and modifying the target of the drug.
But, not by moving away from the drug.
Thus, the correct answer is D.
Cultivation of Bt cotton has been much in the news. The prefix "Bt" means
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"Barium-treated" cotton seeds
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"Bigger thread" variety of cotton with better tensile strength
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Produced by "biotechnology" using restriction enzymes and ligases
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Carrying an endotoxin gene from
Bacillus thuringiensis
Explanation
Bacillus thuringiensis
(Bt) is a Gram-positive bacterium that produces crystals during sporulation. These crystals comprise ~130 kDa protoxins called as crystal proteins which are potent and highly specific insecticides. Once ingested by specific host, these crystals dissolve in the alkaline conditions of the gut thereby activating the protoxins. The active toxins then bind to receptors on midgut epithelial cells, become inserted into the plasma membrane where they form pores leading to cell death through osmotic lysis. This special feature of Bt toxin was explored in genetic engineering to produce genetically modified variety of cotton known as "Bt cotton" which produce the insecticide. Option D is the correct answer.
Which one of the following is a matching pair of a drug and its category?
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Amphetamines - Stimulant
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Lysergic acid diethylamide - Analgesic
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Benzodiazepam - Pain killer
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None of the abve
Explanation
Amphetamine is an antisleep drug, which stimulates CNS. Lysergic acid diethyamide (LSD) is the most potent hallucinogen.
Benzodiazepam is a sedative, which switches of the CNS and is antianxiety. Heroin is a psychotropic drug, which acts on the brain and alters behavior, consciousness and capacity of perception.
Thus, the correct answer is option A.
Pollution from animal excreta and organic waste from kitchen can be most profitably minimized by
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Storing them in underground storage tanks
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Using them for producing biogas
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Vermiculture
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Using them directly as biofertilizers
Explanation
Animal excreta and kitchen wastes are the biodegradable waste and can be reduced when it is exposed to moisture and sunlight by the process of anaerobic fermentation. This happens due to the bacteria present in the matter which acts in the absence of oxygen. As a result, a lot of methane and nitrous oxide is produced and released into the atmosphere. Biogas is the result of this decay and it is an energy source. Thus, the correct answer is option B.
The carnivorous fish
Gambusia
, introduced in the lakes, ponds, etc., control a deadly disease in India, feeds on the larvae of ?
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Nephantis
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Dragonfly
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Anopheles
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All of the above
Explanation
Gambusia affinis,
a native of the coastal waters of the United States from New Jersey southwards, was introduced into India about 40 years ago from Italy and Thailand.
The species can successfully survive in overcrowding conditions.
Found in freshwater, brackish water, and salt marshes with high salinity.
It feeds on aquatic and terrestrial insects.
A single carnivorous fish that can consume mosquito larvae of
Anopheles
equal to its own weight each day and hence, known as mosquito fish.
So, the correct answer is '
Anopheles'
Select the correct statement.
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Acetobacter aceti
produces citric acid.
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Saccharomyces cerevisiae
is used as clot buster.
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Penicillium notatum
restrict the growth of
Staphylococci
.
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Methanogens are found in aerobic conditions.
Explanation
Penicillium notatum
restricts the growth of
Staphylococci
.
Acetobacter aceti
produces acetic acid.
Saccharomyces cerevisiae
is used for the commercial production of ethanol and in baking.
Streptococcus
produces streptokinase which is modified by genetic engineering to be used as a 'clot buster' for removing clots from the blood vessels of patients who have undergone myocardial infarction leading to a heart attack.
Bacteria that produce methane are collectively called methanogens, and one such common bacterium is
Methanobacterium
.
These bacteria are commonly found in the anaerobic sludge during sewage treatment.
So, the correct answer is '
Penicillium notatum
restricts the growth of
Staphylococci
.'
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Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
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Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
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Assertion is correct but Reason is incorrect.
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Both Assertion and Reason are incorrect.
Explanation
Use of fertilizers greatly enhances crop productivity. The use of manure and composts as fertilizers is probably almost as old as agriculture. Modern chemical fertilizers include one or more of the three elements that are most important in plant nutrition nitrogen, phosphorus, and potassium. Of secondary importance are the elements sulfur, magnesium, and calcium.
Fertilizers enhance the natural fertility of the soil or replace the chemical elements taken from the soil by previous crops.
Irrigation is also important in increasing crop productivity. As the plants require water for their survival.
So, the correct answer is option B.
Azolla
is used as a biofertilizer, because it
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Multiplies very fast to produce massive biomass
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Has association of nitrogen-fixing
Rhizobium
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Has association of nitrogen-fixing
Cyanobacteria
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Has association of
Mycorrhiza
Explanation
Azolla
can be used as a biofertilizer as
cyanobacteria
.
Cyanobacteria
live in symbiotic association with the roots. As a result,
Azolla
-
Anabaena
can fix almost three times more atmospheric nitrogen than legumes. Typical rates for legumes are 400 kg of nitrogen per hectare per year those for
Azolla-Anabaena
are 1100 kg of nitrogen per hectare per year.
So, the correct answer is option C.
Which one of the following is regarded as a biofertilizer?
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An association between pteridophytes and cyanobacteria
Anabaena
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An association between gymnosperms and
Nostoc
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An association between legume and
Rhizobium
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All of the above
Explanation
Cyanobacteria either free-living or symbiotic are considered as biofertilizer because they fix atmospheric nitrogen in term of nitrates and nitrites by a biological process like
Rhizobium.
Blue-green algae belonging to a general
Cyanobacteria
genus,
Nostoc
or
Anabaena
fix atmospheric nitrogen and are used as inoculations for paddy crop grown both under upland and lowland conditions.
So, the correct answer is option D.
Which of the following antibiotics is not correctly matched with the source from which it is obtained?
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Penicillin -
Penicillium chrysogenum
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Bacitracin -
Bacillus licheniformis
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Griseofulvin -
Penicillium griseofulvum
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Streptomycin -
Bacillus griseus
Explanation
Streptomycin is obtained from
Streptomyces griseus
. It is found useful in the treatment of meningitis, pneumonia, tuberculosis and local infections.
Cow dung is appropriately used as
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Manure
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Perfume
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Medicine
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Building material
Explanation
Cow dung is available in plenty in India. It is used as manure or pattings for fuel. The cow dung solution has antifungal and insecticide properties. The application of cow dung also improves soil salinity and alkalinity. The presence of this manure helps in better nitrogen fixation through rhizobia.
So, the correct answer is option A.
Bacteria involved in formation of gobar gas are
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Obligate aerobes
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Facultative anaerobes
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Obligate anaerobes
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Both B and C
Explanation
Biogas is produced from the fermentation of organic matter by the action of microbes. Such microbes are anaerobic i.e. they carry out fermentation in the absence of oxygen. Microbes which produce biogas are methanogenic bacteria which can be obligate anaerobes or they can be facultative anaerobes. Obligate anaerobes function only in absence of oxygen i.e. anaerobic conditions. Facultative anaerobes are the bacteria which normally function in aerobic conditions but they can switch to anaerobic respiration if oxygen is absent. Hence, both options B and C are correct.
So, the correct answer is 'Both B and C'.
What is the significance of $$CO_{2}$$ in bakery industry?
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It makes the bread soft and fluffy
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It makes the bread porous
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It increases the volume
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All of the above
Explanation
In the bakery, the yeasts cells are used for the production of fermented products.
The fermented products produced in the bakery include cake, biscuits, and bread. The yeast cells are added to the dough.
The fungus performs anaerobic fermentation. The fungus utilizes the fermentable sugars and converts them to ethanol and carbon dioxide.
The carbon dioxide gas causes the dough to rise the volume and become soft and fluffy. The carbon dioxide bubbles get trapped in the dough and when baking is done, these bubbles break and form pores.
Thus, the correct answer is option D.
What is the process called due to which idli and dosa makes it fluffy and soft?
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Pasteurisation
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Fermentation
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Vaccination
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None
Explanation
Saccharomyces cerevisiae
is the fungus that is commonly known as baker's yeast. The yeast cells are added to the batter of idli and dosa. The fungus performs anaerobic fermentation. The fungus utilizes the fermentable sugars and convert them to ethanol and carbon dioxide. The carbon dioxide gas causes the dough to rise and become soft and fluffy. The carbon dioxide bubbles gets trapped in the dough and when baking is done, this bubbles break and forms pores.
Thus, the correct answer is option B.
Producer gas differs from biogas in having
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Methane
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Carbon monoxide
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$$CO_2$$
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Formed by fermentation
Raw material used in formation of producer gas is
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Saw dust and wood chips
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Crop residue
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Agroindustry wastes
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All of the above
Polluted water can be purified by using
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Micro-organisms
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Algae
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Pesticides
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Both A and B
Explanation
Water pollution due to organic sources like pollution due to sewage can be prevented by treating sewage before passing into the watercourse
, in sewage or effluent treatment plants (ETP).
Domestic sewage primarily contains biodegradable organic matter, which readily decomposes by bacteria, algae, and other micro-organisms, which can multiply by using these organic substances as substrates and hence reduce some of the components of sewage.
Thus, the correct answer is option D
A chemical substance produced by a microorganism for inhibiting the growth of another is
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Antibody
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Antibiotic
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Aflatoxin
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Antiallergic
Statin is used for
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Lowering LDL cholesterol
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Lipid digestion during ripening of cheese
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Detergents
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Flavouring edibles
Methanogens converts
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Methyl alcohol into methane
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Formic acid into methane
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Acetic acid into methane
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All of the above
Tissue plasminogen activator is
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A vitamin
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An electric device
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An enzyme
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A chemical that stimulates tissue differentiation
Biogas production is
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Single step aerobic process
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Two step aerobic process
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Three step aerobic process
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Three step anaerobic process
Primary sludge is used for
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Preparation of compost
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Preparation of manure
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Biogas production
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All of the above
Dosa and Idli are preparations of
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Wheat flour
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Rice
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Rice and Black gram
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Wheat and Black Gram
Antibiotics are drugs commonly used to cure diseases of.
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Fungi
0%
Viruses
0%
Protozoans
0%
Bacteria
Explanation
Antibiotics are chemical substances released by one microorganism either to kill or to pacify other microrganisms, in medicine usually this term is associated with curing of bacterial diseases
In biogas plant which group of bacteria is found?
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Archaebacteria
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Myxobacteria
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Cyanobacteria
0%
Mycobacteria
Sausages are fermented
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Vegetables
0%
Meats
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Milk
0%
Sauce
Processed cheese is
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Soft cheese
0%
Blended cheese
0%
Ripe cheese
0%
Hard cheese
Which bacterium is used extensively as biopesticide?
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Bacillus subtilis
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Streptococcus lactis
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Bacillus thuringienesis
0%
Lactobacillus acidophilus
Explanation
Bacillus thuringienesis is a potent agent that can function as a biopesticide.
Correct answer-C
Modern detergents contain enzyme preparation of.
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Thermoacidophiles
0%
Thermophiles
0%
Acidophiles
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Alkaliphiles
Explanation
The enzymes used in detergents must be able to perform the task in the presence of anionic and non-anionic detergents,soaps,oxidants, etc at pH between 8-10.5%.Alkaline detergent contain enzyme preparation of alkaliphiles.
Correct answer-D
Sewage treatment process in which part of decomposer bacteria is recycled into starting of the process is called.
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Cyclic treatment
0%
Primary treatment
0%
Tertiary treatment
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Activated sludge treatment
Explanation
A part of the activated sludge is pumped back into the aeration tank to serve as an inoculum in activated sludge treatment.
Correct answer-D
A common biocontrol agent for plant diseases is?
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Bacillus thuringiensis
0%
Glomus
0%
Trichoderma
0%
Baculovirus
Explanation
Trichoderma fungus is a common biological control for a range of plant pathogens.
Correct answer-C
Which one of the following is useful in rice fields?
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Rhizobium
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Clostridium
0%
Anabaena
0%
Ferrobacterium
Biofertilizers include
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Nitrogen fixing bacteria
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Mycorrhiza
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Nitrogen fixing cyanobacteria
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All of the above
Some blue green algae can be used as biofertilizer as they are
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Photosynthesis
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Surrounded by mucilage
0%
Growing every where
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Capable of fixing nitrogen
Explanation
Some cyanobacteria can fix atmospheric nitrogen in anaerobic conditions by means of specialized cells called heterocysts. These heterocyst forming species are specialized for nitrogen fixation, and are able to fix nitrogen gas into ammonia, nitrites, or nitrates, which can be absorbed by plants and converted to proteins and nucleic acids as nitrogen cannot be directly absorbed by plants. Therefore, some of the cyanobacterial species are used as biofertilizers.
So, the correct answer is '
Capable of fixing nitrogen'
They help in increasing soil fertility.
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Pseudomonas and cereals
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Bacillus and Penicillium
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Salvinia and Marsilea
0%
Nostoc and legumes
Explanation
Nostoc and legumes help in increasing soil fertility by nitrogen fixation in the soil.
Correct answer-D
The product of which has been commercialised for lowering blood cholesterol.
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Trichoderma polysperma
0%
Monascus purpureus
0%
Saccharomyces cerevisiae
0%
Aspergillus niger
Explanation
Monascus yeast are commercially being used for lowering blood cholestrol levels.
Correct answer-B
A fern commonly inoculated to paddy fields is
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Azolla
0%
Marsilea
0%
Salvinia
0%
Anabaena
Microbe yielding 'clot buster' for myocardial infraction is?
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Penicillium notatum
0%
Clostridium butylicum
0%
Streptomyces species
0%
Azotobacter aceti
Explanation
Streptomyces produces clot busters helpful for patients who have undergone myocardial infraction.
Correct answer-C
Which is used as biofertilizer?
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Azolla
0%
Marchantia
0%
Funaria
0%
Dryopteris
Biofertilizer is?
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Manure
0%
Enriched manure
0%
Nutrient rich organisms
0%
Composited manure
Explanation
A
biofertilizer
is a substance which contains nutrient rich living microorganisms which colonize the rhizosphere or the interior of the plant and promotes the growth of the plant or the seed by increasing the availability of primary nutrients to the plant.
Which one of the following is a free-living obligate anaerobic bacterium?
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Clostridium
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Rhodospirillum
0%
Azotobacter
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Bacillus subtilis
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